This application relates to improvements in apparatus of the type disclosed and claimed in U.S. Pat. No. 3,557,817 to Edwin H. Royse entitled "Control for Mixing Fluids of Different Specific Gravity".
The above related patent discloses a free floating hydrometer in apparatus adapted to automatically control the specific gravity of liquid in which the hydrometer is floating. Such apparatus offers substantial improvements over devices previously developed in that the hydrometer was not employed to exert force upon mechanical apparatus for opening and closing switches.
U.S. Pat. No. 3,848,618 to Edwin H. Royse describes and illustrates an improvement over the hydrometer controlled apparatus described in the aforementioned patent in that the hydrometer has been eliminated to maximize the effect of external forces upon the system. However, additional flexibility has been found necessary in the industry and a need has arisen to improve on the basic apparatus disclosed in U.S. Pat. No. 3,848,618.